I am struggling to understand exactly what is happening when you return a new object from a function in go.
I have this
func createPointerToInt() *int {
i := new(int)
fmt.Println(&i);
return i;
}
func main() {
i := createPointerToInt();
fmt.Println(&i);
}
The values printed returned are
0x1040a128
0x1040a120
I would expect these two values to be the same. I do not understand why there is an 8 byte difference.
In what I see as the equivalent C code:
int* createPointerToInt() {
int* i = new int;
printf("%#08x
", i);
return i;
}
int main() {
int* r = createPointerToInt();
printf("%#08x
", r);
return 0;
}
The address returned is the same:
0x8218008
0x8218008
Am I missing something blindingly obvious here? Any clarification would be greatly appreciated!
You are printing the address of the pointer here fmt.Println(&i);. Try this:
func main() {
i := createPointerToInt();
fmt.Println(i); //--> Remove the ampersand
}
i is the pointer returned from createPointerToInt - while &i is the address of the pointer you are trying to print. Note in your C sample you are printing it correctly:
printf("%#08x
", r);
^No ampersand here
Change &i to i. You are printing address of i while you should print the value of i.
func createPointerToInt() *int {
i := new(int)
fmt.Println(i);
return i;
}
func main() {
i := createPointerToInt();
fmt.Println(i);
}
But how come in your original code the addresses of the two pointers (not memory addresses the pointers are pointing too) are different?
func main() {
i := createPointerToInt();
fmt.Println(&i);
}
Is equivalent to:
func main() {
var i *int // declare variable i
i = createPointerToInt(); // assign value of
// a different i that was
// declared and initialized
// inside the function
fmt.Println(&i);
}
Edit:
To print the address of a struct you need to use:
fmt.Printf("%p
", &your_struct)
For example: